Drilling bit



L. B. HELLMAN DRILLING BIT July 14, 1942.

Filed Jan. 51, 1941 2 Sheets- Sheet l 4605. fle/fmaz) INVENTOR W' 6 )4} BY m0 ATTORNEYS July 14, 1942- 1.. B. HELLMAN DRILLING BIT Filed Jan. 51, 1941 2 SheetS Sheet 2 4605 Hal/ma):

mmyamwaa 2 (B u I ATTORNEYS Patented July 14, 1942 UNITED STATES PATENT OFFICE DRILLINGJBIT Leo B. Hellman, Alvin, Tex. Application January 31, 1941,,Scria'l No..376,91-1

1 Claim.

This invention relates to improvementsin drilling bits and especially islconoerned with a novel bit having replaceable or'at leastren'ewable cutter elements.

It is a primaryobject of this invention to .provide anovel drilling bit useful in the boring of oil wells and the like wherein the cutterelements are renewable during use without, interruptiton nelpassing axially through thebit, whereas-replacement of cutter elements'in existing types of bits has 'in :the past required shutdown'ofopera'tion of the drilling jig, withdrawal of the drill and replacement or adjustment of the bit.

Features of the novel drilling bit according to this invention are its simplicity and ruggedness of construction, the former well adapting the de vice to the requirements of mass production in manufacture and the latter assuring long useful life without necessity for repair.

Other objects, advantages and features of the new and improved drilling bit according to the present invention will be apparent to those skilled in this art during the course of the following description.

Regarded in certain of its broader aspects, the novel drilling bit according to the present invention comprises a body having a fluid passage extending therethrough, a rounded head on the body, slidingly mounted cutters in said head extensible into cutting position, and means operable from within the fluid passage for moving the cutters into extended position.

In order to facilitate a fuller and more complete understanding of the present invention a specific embodiment thereof, herein illustrated, will be hereinafter described, it being clearly understood, however, that the illustrated embodiment, although presently preferred, is provided solely by way of example of the practice of this invention and not by Way of limitation thereof except insofar as the invention is recited in the subjoined claim.

Referring then to the drawings,

Figure 1 is substantially a ide elevational view taken along theiline 55 thereof, and

:Fig. 6 is a horizontal sectional View of Fig. 4 taken along the line6.6 thereof.

The illustrated preferred embodiment of the instant inventiongenerally designated by the reference character It comprises a shank or body portion ll having an openin Ila extending axially therethrough constricted at an intermediate portion Ilib and further, constricted at the portion'l Ic branching into the outlets Hd' formed in the rounded end portion 1 le of the bit body. Asheath member- I 2 surrounds'the portion of the bit body located directly behind the rounded end or head I le and serves to hold internal parts of the bit in preselected relationship as hereinafter-gwillbe made more apparent. Cutter ele- .ments 13 and .l l freely slidingly, mounted in openings formed in the bit head are provided with cutting end portions lid and Ida. respectively and the opposite ends of the cutter elements are formed with slots I31) and Mb respectively to facilitate connection with threaded stems l5 and I5 by means of the pins I! and 13 held in portions of the stems and received in the slots. The stems l5 and I6 are threaded along a portion thereof as designated by the reference characters I5a and I60. and are received in axially extending openings formed in collars I9 and 23 whereby rotation of the collars is translated into axial movement of the threaded stems, thereby causing the cutter elements I3 and IE to move within the cutter head. The collars l9 and 29 are freely rotatably mounted within the bit body but are provided with radially extending formations I90 and 20a respectively formed on the ends thereof which abut against portions of the body to prevent axial motion of the collars. Channeled pieces 2| and 22 fitting into openings formed in the body H and held therein by the sleeve l2 serve further to constrict axial motion of the collars I9 and 20 while permitting free rotation f the collars.

The upper ends of the collars l9 and 20 are provided with integrally formed spur gears 23 and 24 for facilitating rotation of the collars as hereinafter will be described. A shaft 25 carrying a second set of spur gears 21 and 28 meshing with the spur gears 23 and 24 is mounted within the body II extending transversely therein substantially as shown. The spur gears 21 and 28 are fixedly mounted upon the shaft and rotate therewith. As will be apparent to those skilled in this art, rotation of the shaft 25 results in sliding motion of the cutter elements I3 and I4 hereinabove described.

The means for causing rotation of the shaft 25 will now be described, reference being made especially to Figs. 4, and 6 wherein the reference character 29 designates a pinion gear freely rotatably mounted upon the shaft 25 and coupled by means of a ratchet clutch 30 with the spur gear 28 whereby unidirectional rotation is imparted to the spur gear by oscillation of the pinion. The elements of the ratchet clutch 3B are pressed into engagement by a spring 3I sleeved about the shaft 25 whereby the parts normally assume substantially the relation-ship shown in Fig. 6. A sliding bar 32 having a toothed rack end portion 32a is mounted in portions of the body II wh'ereby the toothed end portion of said bar meshes with the pinion 29. The bar normally is urged by the spring 33 acting against a washer 34 which in turn presses against a pin 35 mounted in the bar to cause the bar to assume one of the extreme positions of its sliding motion which, as will be apparent to those skilled in the art from the foregoing description, reciprocation of the bar 32 will cause unidirectional rotation of the spur gear 28 and shaft 25 whereby the collars I9 and 20 will be rotated causing advancement of the stems I5 and I6 and the cutter elements I3 and I4.

A lever arm 35 fulcrumed upon a portion 36 of the body II is pivoted to the free end of the bar 32 and the opposite end of the lever arm is provided with a hook formation 3I'whereby a loop A positioned within the fluid passage I la can be used to reciprocate the bar 32 through operation of the lever.

In use the bit is employed as is an ordinary drilling bit and when, upon occasion, due to wear or for other reasons it is desirable to renew the cutter surfaces of the cutter elements, a loop is positioned within the fluid passage of the bit and engaged with the hook elements on the end of the lever whereby the lever can be oscillated causing reciprocation of the pinion meshing therewith which, functioning through the unidirectional ratchet clutch, serves to rotate the spur gears and collars advancing the stems and the cutter elements, at such time as it is desirable to replace the cutter elements, the sleeve or sheath I I is removed exposing internal parts and permitting the repairs easily to be made.

It is to be understood that this invention is capable of extended application and is not confined to the precise illustrated forms nor described construction and, therefore, such changes and modifications may be made th'erein as do not affect the spirit of the invention nor exceed the scope of the appended claim.

Having thus described the present invention, what it is desired to secure by Letters Patent is:

A drilling bit comprising an elongate essential- 1y cylindrical body having a fluid passage extending axially therethrough, a rounded head on one end of said body, slidingly mounted cutters in said head extensible into cutting position, means for moving the cutters into extended position comprising threaded stems attached to said outters, collars rotatably mounted Within said body in a manner precluding motion along the axis of rotation of the collars, said collars being internally threaded to receive and engage with said stems whereby rotation of the collars causes the cutters to move into extended position, means for rotating said collars comprising a shaft, a first set of spur gears on the shaft, a second set of spur gears on the collars meshing with the first set of spur gears, a pinion freely rotatably mounted on the shaft, a unidirectional ratchet clutch connecting the pinion and. one of said first set of spur gears, a freely sliding rack, spring urged in one direction, meshing with said pinion, a lever arm connected to said rack for reciprocating same, and. a hook element on one end of said lever within the fluid passage whereby the lever can be operated by a loop engaging said hook element.

LEO B. HELLMAN. 

